On Thu, Jul 30, 2026 at 02:39:27AM -0400, Gregory Price wrote: > On Thu, Jul 30, 2026 at 12:58:22AM -0400, Gregory Price wrote: > > On Wed, Jul 29, 2026 at 05:48:38PM +0100, Lorenzo Stoakes (ARM) wrote: > > > > > > This will be necessary for determining the address of a folio's index > > > within a VMA when the folio belongs to a MAP_PRIVATE file-backed VMA but > > > has been CoW'd, and thus is anonymous, once the anonymous VMA page offset > > > field is used for the reverse mapping. > > > > > > > This is a doozy of a sentence... > > > > ... determines the address of a folio's index within a VMA when > > - the folio belongs to a MAP_PRIVATE file-backed VMA, but > > - <The VMA> has been cow'd > > - thus <The CoW'd VMA> is anonymous (as well) > > - The original VMA may or may not also be marked anonymous? > > (just clarifying, could be original mapper or a COW that COWs) > > > > Ow, my brain. One question below > > > > After re-reading the cover-letter again - my note here is wrong and > my brain hurts more. > > ... determines the address of a folio's index within a VMA when > - the folio belongs to a MAP_PRIVATE file-backed VMA, but > - <The Folio> has been CoW'd > - thus <The CoW'd Folio> is <now marked> anonymous > - The original folio may or may not have been anonymous > (depending on whether it, itself, was a CoW copy)
Yeah :) this message is meant to be effectively a placeholder for 'there's a good reason for doing this' :) I go to greater lengths to explain in the bits that actually implement it. > > Lorenzo you are truly doing Darwin's work untangling all of this. Thanks :) This is really painful stuff and trying to get to scalable CoW the 'right way' (i.e. several series and probably 3 figures of patches) is a slog, but once in place will be worthwhile (and also save a bunch of memory :) > > ~Gregory
